Current production motor vehicles, such as the modern-day automobile, are originally equipped with a steering system that allows the driver to maintain a desired course for the vehicle and to control directional changes of the vehicle. A conventional steering system is provided with a hand-operated steering wheel that is manipulated by the driver to input a desired direction of travel for the vehicle. The steering wheel is mounted via a central hub to a collapsible or non-collapsible steering column assembly. Telescoped shafts of the collapsible steering column interconnect the steering wheel with the vehicle's steering mechanism, the most common of which is the rack-and-pinion steering architecture. In this architecture, a pinion gear at the distal end of a steering shaft is intermeshed with a linear gear bar, known as a “rack.” When the steering wheel is rotated, the pinion gear spins, causing the rack to move rectilinearly. A tie rod at each end of the rack is connected to the steering arm of a wheel's spindle; the moving rack and tie rod pivot the spindle to thereby turn the wheel. Driver input can be augmented with hydraulic or electric Power Assisted Steering and, in some modern production vehicles, assisted with computer controlled motors known as Electric Power Steering.
Generally, the internal combustion engine (ICE) of a motor vehicle can be operated over various speeds. An engine can operate, for example, at a low (idle) speed with the powertrain in an idling state of operation, and can also operate at a lower (park) speed with the powertrain in a parked state of operation. Each speed of the engine can correlate with a distinct vibrational frequency that may be transmitted to the operator through the steering wheel and steering column assembly of the steering system. Vibrations induced by the vehicle's powertrain (including the engine and transmission) are typically classified as “resonant excitation” or as “deterministic vibration.” Road-induced vibrations can also be experienced by the operator through the steering wheel and column during operation of the vehicle, e.g., if driving over irregularly spaced road displacements, such as potholes and speed bumps. These road induced vibrations are typically classified as “forced excitation” or as “random vibration.” It is oftentimes desirable to attenuate powertrain and road induced vibrations to improve the driver's experience during operation of the vehicle.